1. Field of the Invention
This invention comprises an improvement on U.S. Pat. No. 4,325,037 which corresponds to European Patent No. 0 016 979 which disclose a filter having acoustic waves traveling in a substrate or close to the surface. So as to avoid triple transient signal in such a filter, the frequency of the more narrow-banded of two transducers in the filter is set to one of the other of two reflector frequencies f.sub.R1 or f.sub.R2. This technique is also used with a reflector arrangement which is composed of an input transducer and output transducer as well as reflector structures. Such devices are illustrated in FIG. 4 of U.S. Pat. No. 4,325,037 and the specification and description of U.S. Pat. No. 4,325,037 is hereby incorporated by reference into the present disclosure as background material.